The present invention relates to a smoke detector with a transmitter for a radiation that can be detected by a receiver.
Smoke detectors are known and on the market in various forms and configurations. The present invention relates in particular to smoke detectors that are flush with a ceiling, as described in particular in DE 199 51 403 B4. There, a radiation is emitted from a transmitter in a ceiling through a covering into free space, this radiation is reflected at least partly by the smoke and is registered by a receiver behind the covering. A control program detects a deviation of the reflection and analyzes whether the deviation originates from smoke or from a foreign body, a multitude of detection processes being carried out within a unit of time and an alarm only being set off when a specific number of detection processes are positive in succession and, to distinguish between smoke and foreign bodies, a distinction is established between a continuous increase in the reflection, as in the case of smoke, and an abrupt increase in the reflection, as in the case of a foreign body. Furthermore, for the self-monitoring of this smoke detector, the transmitter is assigned a receiver of its own for receiving a radiation reflected from the covering and the receiver is assigned a transmitter of its own in front of the covering.
The present invention addresses the problem of further improving such smoke detectors and, in particular, monitoring better the surroundings of the smoke detector itself.